This layout is epic. You've done an amazing job at stuffing all this in such a small volume. I didn't realize how small it was until I saw it inside the enclosure. It's really impressive.
But I can't see how you power it... Is there a battery inside the enclosure?
And I just noticed, why are you working inside a car?
Ha, Ha. Yes, I am working inside a truck! in fact i built this whole amp in my work truck. The reason is that i am an electronics tech, and at times i have to work out in the field.
Yes, there is a battery inside the enclosure, it is a 900ma 3 cell li-po pack with a protection PCB, i purchased the cells from all-battery(dot)com, part number 463455, they are; 4.6mm thick, 34mm wide and 55mm long, hence the 46-34-55 part number.
As for the layout even i was surprised that i could get it all to fit. I have already revamped the board though, and the layout is much better, and i gained a little board space to boot. The one drawback (and big improvement) to the new layout, is that it places SMD caps very close to the op-amp power pins on the backside of the op-amp daughter card. The caps are pricey, and mouser had 7 of them 505-PET28-1/63/10 , i bought 6, so there is one left!
I am trying to find an alternative, I want to keep the SMD cap because it allows me to place the cap very, very close to the op-amp, this is a good thing.
as I stated I am working out in the field, so getting critical listening time in is very hard to do. I did listen to a few songs last night with My M50's, I was very tired, but I liked what i heard, a lot!
Next big project for this amp will be to figure out a way to socket the op-amp board, i have been looking for a solution to this since i started this amp. Mill-Max makes some nice sockets that are low profile an designed to press into the PCB, the problem is that they need a machined round pin (.012-.018 or so dia.) to work well. They don't offer a right angle male pin that will work. because the op-amps pretty much have to be SOIC8 packages, rolling op-amps is a huge ordeal. My new design however, if I can get some sort of socket arraignment, would allow the individual op-amp boards to be swapped. So it would be akin mounting the op-amp to a brown dog adapter, only with the feedback and gain resistors and caps on the board, and just swapping out the assembly.
And I want to order up some OPA827's to try, I keep hearing good things about these op-amps and they have pretty good voltage specs for this amp. I do like the 1641's I hope to get more ear time on them but for the few hours i have listened to them i haven't found anything i dislike about them.